There is about one motor vehicle for every eleven persons on Earth. More than 400 million cars and trucks are operated throughout the world. Aircraft, automobiles and boats are operated at speeds that impart considerable kinetic energy to passengers. Injury to passengers results if this kinetic energy is not dissipated gradually. Each year more people are killed or injured in motor vehicle accidents than were killed or injured in the Vietnam or Korean wars. Motor vehicles involved in collisions need better protection for passengers. Air bags have shown positive results in protecting crash victims. Air bags presently used for crash protection of passengers produce numerous problems and are inadequate in several ways including:
1. Solid propellants such as azide compounds used to inflate air bags produce objectional emissions and residues. PA1 2. Solid propellant systems are dangerous in the manufacturing plants that produce them and have caused many accidents. PA1 3. Chemicals and manufacturing processes used in the production of solid propellants produce environmentally objectionable residues that pose disposal problems. PA1 4. Ignition systems for conventional air bag propellant systems are uncertain and produce objectionable byproducts. PA1 5. Common problems of hydrocarbon and ammonia-based gaseous and liquid-state or "fluid" fuels that have been used for air bags include toxicity before combustion and the production of toxic products upon combustion or chemical reaction. PA1 6. Fluid fuel must be mixed with an oxidant and delivered in ignitable proportions in the spark gap of a spark source at the exact time needed to initiate combustion. This is difficult because of varying degrees of fuel penetration and deflection as a result of widely varying velocities of air entry into the geometry of the fuel spray pattern. PA1 7. Fluid fuel directed towards the spark source from the fuel injector for purposes of producing a suitable mixture of fuel and oxidant for spark ignition invariably result in substantial amounts of fuel impinging on heat-robbing areas of the enclosure defined by the air bag components around the spark source. This results in quenching of the combustion and/or heat degradation to air bag components and often seriously compromises the integrity of the air bag by under-inflation, misshaped bags because of shriveling, and/or rupture and leakage upon impact by the crash victim. PA1 8. Previous attempts to use fluid fuels failed to be dependable because of gradual leakage of fuel from storage during prolonged stand-by conditions that are typical to transportation applications. PA1 9. Degradation of adequate rapid-pressurization capabilities has been a problem in previous air-bag inflation systems due to undetected gradual leakage and/or slow reaction of mixtures of fuel and oxidant during prolonged storage. PA1 10. Accidental deployment of air bags due to erroneously initiated reactions between fuel and oxidant mixtures poses a serious hazard to occupants of vehicles equipped with prior-art systems that store mixtures of fuel and oxidant. PA1 11. Present air bag systems are incapable of meeting needs for small, medium, and large air bag inflation requirements without overheating or over pressurization of small bags in a system that is adequate for inflation of large bags. PA1 12. Efforts to overcome the problems arising from undesirable fuel-air ratios at the spark source during the critically short duty cycle required for air bag inflation have resulted in expensive and complicated gadgetry and electronic control systems.
The use of hydrogen as fuel in air bag inflation systems offers attractive characteristics, particularly including the fact that hydrogen is not poisonous, rapid combustion, and virtually no pollutive emissions. However little success has resulted from efforts to provide practical solutions for reducing the problem of thermal degradation of the air bag around the spark source. Another problem has been incomplete combustion due to quenching in instances that sufficient heat sinking by metal plates, split phase materials, and liquid coolants are provided to prevent such thermal degradation.